Hydraulic power systems have generally been limited to industrial and commercial uses because of the high cost of hydraulic cylinders and pumps, the cost of operating and maintaining such systems, the potential for leakage of the hydraulic fluids and the environmental and safety concerns. Although hydraulic systems, such as hydraulic presses, for lifting, pushing or performing other tasks have been used extensively in commercial settings, the true potential of hydraulics has been restricted because of these problems and other limitations associated with the current systems.
Traditionally hydraulic cylinders have been made from metal tubing having relatively thick walls and extremely round, smooth bores. The thickness is needed to withstand the hydraulic pressure generated by the pressurized hydraulic fluid and to prevent the cylinder from excessive expansion under the hydraulic pressure. The bores must be extremely smooth and round to minimize friction and facilitate the movement of the piston relative to the inner wall of the cylinder and to minimize leakage. The required thickness of the cylinder and the cost and time involved in machining a metal bore with the requisite precision combine to make presently available hydraulic cylinders too expensive for use in many settings. The high cost of current hydraulic systems is also attributable to the type of pump and fluid which is dictated by the characteristics of metal cylinders.
The hydraulic force of a given hydraulic system is generally the product of the area of the inside diameter of the cylinder and the pressure of the fluid used to raise the piston to accomplish the intended task. Therefore, an equivalent amount of force can be generated by using a cylinder with a large diameter and low fluid pressure or a cylinder with a smaller diameter and a high fluid pressure.
However, because currently available hydraulic cylinders are so expensive, it has typically been preferable to provide a high fluid pressure with a cylinder of a small diameter. Unfortunately, the savings made in using smaller metal cylinders is off-set by the high costs of high pressure fluid pumps. There are also serious safety problems that result when such highly pressurized fluid escapes through a rupture or leak in the system. Because of increasing energy costs, the cost of running these high powered pumps has become another factor limiting the potential uses of hydraulic systems. Furthermore, to minimize the corrosion of metal cylinders used in current hydraulic systems, the hydraulic fluid used is typically an expensive and messy petroleum-based liquid. Thus, Not only are such fluids difficult to maintain and dispose of, but they are also a safety hazard since they can easily ignite.
Thus, for economic reasons, as well as other considerations, typical hydraulic systems employ small cylinders with extremely strong fluid pumps which use expensive, hydraulic fluids to attain the required amount of force to accomplish a given task. In short, the high cost of hydraulic cylinders coupled with the high cost of high pressure pumps and fluid to obtain the required amount of force to perform a given task have resulted in limited applications of an otherwise remarkably adaptable system that could have an endless number of viable applications.